.main {
	width: 100vw;
	height: 100vh;
	/* flex容器 */
	display: flex;
	/* 设置主轴方向为垂直方向 */
	flex-direction: column;
}

.header {
	width: 100vw;
	height: 100px;
	flex: 0 0 auto;
	border: 5px solid #1B6D85;
	/* 背景图片 */
	background: url(../img/header.jpg) no-repeat center center fixed;
	background-size: cover;
}

.middle {
	width: 100vw;
	flex: 1 1 auto;
	border: 5px solid #255625;
	/* flex容器 */
	display: flex;
}

.footer {
	width: 100vw;
	height: 100px;
	flex: 0 0 auto;
	border: 5px solid #FF6600;
}

.menu {
	width: 200px;
	height: 100%;
	flex: 0 0 auto;
	border: 5px solid #8A6D3B;
}

.content {
	height: 100%;
	flex: 1 1 auto;
	border: 5px solid #C7254E;
	/* 背景图片 */
	background: url(../img/welcome.jpg) no-repeat center center fixed;
	background-size: cover;
}
